Patent GB-772509-A (GB)
Title: Electronic integrator
IPC: H03M1/00
Filed: 1954-11-24
Abstract: 772,509. Potentiometric voltage measurement. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 24, 1954 (Nov. 27, 1953], No. 34060/54. Class 37. [Also in Groups XIX and XL (b)] An electronic integrator (see Group XIX) integrates a variable quantity presented to it in the form of a trace on a film strip or tape, moving stepwise. At each step a potential is produced proportional to the value of the quantity at that point and this potential is fed to a comparator where it is balanced against a potential produced by a counter, the counter counting upwards continuously to produce a proportionately increasing potential. When the potentials coincide, the comparator causes the count then registered to be added to that on a summation counter recording the integration. The embodiment of integrator described integrates two variables on two summation counters, Fig. 3, showing duplicated film strips 400, 4001, identical comparators C1, C2 and a switching circuit CK for selecting one or the other of the variables with its respective comparator alternately throughout the integration. To describe only apparatus connected with the strip 400 and comparator C1, the trace 401 is followed by a stylus 404 operating a potentiometer 406 to produce the proportional potential. The variable tap 405 of the potentiometer is connected to the grid of a pentode discharge device 411, the cathode of which is connected to a ground bus 202. The anode is connected by a lead 418 to a gaseous discharge device 421. The anode of 421 is connected to a high voltage bus 426, this voltage being higher than that in a plate supply bus 201. The counter potential is connected to the comparators through a discharge device 430, the left-hand triode section of which is associated with the comparator C1 and the right-hand section with comparator C2, by a lead 19. The device 430 is connected by a lead 439 to the grid of the device 421. The lead 19 is connected to a discharge device 440 and smoothing capacitor 441 which prevent spurious relatively short potential fluctuations from causing premature opening of the comparator unit. The device 421 has a stabilizing circuit including a resistor 446 and pentode discharge device 445, the device 445 having its screen grid connected to a source 449 of positive potential via a variable resistance network 448. An output signal from the gaseous discharge device 421 is taken by means of a capacitor 452 across a resistor 451 to the grid of a pentode discharge device 455, the anode 456 of which is coupled by a conductor to a time delay device (not shown). To maintain a linear relation between the input signal on the grid 410 of device 411 and the output applied to the device 421, the relative potential difference between the cathode 414 and screen grid 415 is maintained substantially constant by means including a tetrode discharge device 462, conventional voltage regulator 468 and resistors 466, 471. A triode discharge device 478 is connected across the device 421 in order to extinguish the latter, the anode 479 of the triode being coupled to that 422 of the device 421 and the cathode 481 being coupled to a source of positive reference potential 482 less than the source of positive potential 426. The control grid 480 of the triode 478 is connected to the switching circuit CK connected as a conventional double stability trigger circuit. Qperation.-The potential proportional to the quantity being integrated appears on the grid 410 of the device 411 to vary the conductivity accordingly. The incrementally increasing potential of the counter is fed to the control grid 434 of the device 430 and a correspondingly increasing reference potential is thus fed to the grid 420 of the device 421. When the reference potential reaches a value equal or proportional to (as arranged) the sample potential, the tube 421 will be fired and the device 455 become conductive. A voltage drop is produced across the resistor 460, lowering the potential of the anode 456 and triggering a time delay device (not shown). When the time delay device returns to normal, it operates a gating circuit and switching means (not shown) to permit negative pulses to reach the respective summation counter. To produce positive and negative excursions of the variable, a zero is selected by adjustment of bias potential by the network 448 so that the datum line on the tape corresponds to firing of the device 421 when the counter, having as described a range of 0-19,999, reaches 10,000. U.S.A. Specification 2,717,994 is referred to.